Telephone-exchange system.



B. G. DUNHAM.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. 14, 1915.

Lfiwfi o Patented May 29, 1917.

a an eras later circa.

BERT G. DUNHAM, 0F HAWTHORNE. NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented May 29, 1191?.

Application filed September 1%, 1915. Seriarl No. 50,590.

To all whom it may concern:

Be it known that I, BERT G. DUNHAM, a citizen of the United States, residing at Hawthorne, in the county of Passaic and State of New, Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to circuit arrangements for selector switches employed in automatic telephone exchanges.

The object of this invention is the provision of a simple circuit arrangement for insuring the proper operation of selector switches.

According to one feature of this invention, an electromagnetic means, such as a side switch, controls the selective operation of the selector switch, and is in turn controlled by the restoring magnet of the selector, whereby the actuation of the electromagnetic means is prevented during the restoration of the selector switch,

According to another feature of this invention, the operation of the electromagnetic means is controlled by an operating magnet of the selector whereby the proper restoration of the selector switch is insured in case the calling party abandons the call.

The drawing represents a full automatic telephone system and more in detail the cir-,

cuits of a selector switch, only so much being shown of the telephone system as is necessary for a clear understanding of this invention.

The subscriber at substation 1, desiring to establish a connection with a called subscribers station 2, removes his receiver from the switchhook, causing thereby, in the wellknown manner, the extending of his line to an idle trunk leading to a selector switch 3. A. circuit is closed thereupon from grounded battery through the left-hand winding of a line relay 4, a wiper 5 of an electromagnetic means or side switch associated with selector 3, the calling line circuit, side switch wiper 6, and the right-hand winding of relay 4 to ground. Relay 4 closes a circuit from ground through its armature and front contact, contact 7 (closed in the normal position of selector 3), and the winding of a slowacting relay 8 to grounded battery. Relay 8 closes a circuit from ground through its armature and back contact of a restoring or release magnet 9, and the winding of an escapement magnet 10, to grounded battery.

The calling subscriber proceeds now to set selector 3, in accordance with the numerical deslgnation of the called station, by operatmg lmpulse sending device 11 providedat substation 1. In response to each current lnterruption produced in theline circuit by means of sendin device 11, the relay 4 estab lishes a circuit Irom ground through its armature and back contact, the front contact and armature of magnet 10, side-switch wiper 12 and the winding of a primary magnet 13 to grounded battery. Under the control of magnet 13, the brushes of the selector 3 are moved in a rotary direction. During the vibration of the armature of relay 4, relay 8 being slow to release remains energized and keeps therefore the circuit of magnet 10 closed. As soon as selector 3 leaves its normal position, contact 7 will be opened and a contact 1% closed. During the vibration of the armatures of relay 4. and primary magnet 13, relay 8 is maintained energized by an interrupted circuit extending from grounded battery, through the winding of this relay, contact 14, the back contact and armature of magnet 13, side-switch wiper 12, the armature and front contact of magnet 10, and the back contact and armature of relay 4, to ground. After the calling subscriber has sent' out the desired series of impulses, relay 4 maintains its armature at-.

'tracted, opening thus the circuit of relay 8 are moved into their second position, in

which position magnet 13 is disconnected and a circuit, is closed from grounded battery through the winding of a secondary' magnet 15, the armature and back contact of this magnet, side-switch wiper 12, the'armature and back contact of magnet 10, sideswitch wiper 16, and the front contact and armature of relay 4, to ground. The secondary magnet, by interrupting its own circuit, steps the selector brushes in a vertical direction to hunt for an idle outgoing line in the selected group.

As well known, the busy or idle condition of such outgoing lines is characterized by a battery potential connected to multiple test terminals, such as 17. Supposing that in I this case the idle outgoing lines or trunks are; characterized by a ground connection to terminal 17, and the busy trunks by a battery'connection to this terminal, it will be seen that as soon as a test wiper '18 of selector 3 reaches terminal 17, to which ground is connected, a'circuit will be closed through the armature andback contact of magnet 9, and the winding of escapement magnet 10 to grounded battery. The escapement magnet moves now upon energization the sideswitch Wipers into position 3, disconnecting thereby magnet 15 and extending the calling incoming line through wipers 5 and 6 to a selected outgoing line. The calling subscriber may control the completion of the desired connection in any well-known manner.

' In position 3 of the side switch wipers, line relay is deenergized. I,

Upon the severing of the established connection at the called substation, a ground is connected to terminal 17 (no such ground connection existing during conversation), whereby a circuit is established through wiper 18, side-switch wiper 19, a contactv20 (closed as soon as selector 3 leaves its normal position), and the winding of release magnet 9 to grounded battery. Thls magnetcauses first the release of the side-switch wipers to normal for establishing a locklng circuit extending from ground through the armature and back contact of relay 4:, the

lector 3, 2. e. in the first position of the side switch, the restoration is efiected in the following Inanner: Line relay 4 becomes deenergized and opens the circuit of slow-acting relay 8. Relay 8 remains actuated and maintains magnet 10 energized for a sufficient period to permit the sending of animpulse from ground through the armature and back contact of relay 4, the front contact and armature of escapement magnet 10,

side-switch wiper 12, and the winding of magnet 13 to grounded battery. Magnet 13 moves selector 3 out of its normal position. Relay '8 and therefore magnet 10- become deenergized, the second circuit (extend1ng through contact 14) of relay 8 being open at the back contact of primary magnet 13. Magnet 10 opens the circuit of maet 13 and steps the side-switch Wipers into posimeat ground through the armature and back contact of relay 4, the back contact and lefthand armature-of relay 8, side-switch wiper 19, off-normal contact 20 and the winding of magnet 9, to grounded battery. Magnet 9 controls the release of the side-switch and selector 3 tonormal in the same manner as above described. The circuit of escapement magnet 10 being controlled at the back contact of release magnet 9, magnet 10 cannot become energized and move the side-switch wipers from position 2 into position 3 if the selector brush 1,8 is resting on terminal 17 of w an idle trunk. p

' Should the subscriber abandon. the-call at tion 2. A circuit is now established from any time during the sending out of impulses,

the release of the selector will be accomplished in the same manner as previously explained, If the calling subscriber restores lllS recelver after the completed series of impulses directed "1 control the motion of selector 3, i. e. in position 2 of the side-switch wipers, upon the deenergization of relay 4:,

the locking circuit of release magnet 9is immediately established and this magnet causes the restoration of the side-switch wipers and the selector .mcchanism.

What is claimed is: f

1. In a telephone exchange system, a plurality of lines, a selector switch for inter-. connecting the same, operating means and a restoring magnet for said selector switch, Y

electromagnetic means for controllin the operation of said operating means, a clrcuit for-said electromagnetic means and a contact in said circuit directly controlled by said magnet.

2. In a telephone exchange system, a plurality of lines, a selector switch for interconnecting the same, a primary and a sec ondary magnet for controlling the selective operation of said switch electromagnetic means for controlling said lease magnet for said selector switch, and a contact provided in the circuit of said-means and controlled by the release magnet.

3. In a telephone exchangesystem, a plurality of lines, a selector switch for interconnectingthe same, an operating and arestorin magnet for said switch, means for actuatlng said restoring magnet in oil-normal positions of the selector switch, electromagnetic means for controlling the operation of said selector switch, and a contact provided in the circuit of said electromagnetic means and controlled by said restoring magnet.

4. In a telephone exchange system, a plurality of lines, a selector switch for interconnecting the same, a primary and a secondary magnet for operating said selector switch, electromagnetic. means for controlling the operation of said selector switch,

I magnets, a circult for sa1d electro-magnetic means, a reand a" contact for saidv primary magnet for controlling the operation of said electromagnetic means.

5. In a telephone exchange system, a plurality of lines, a selector switch for interconnecting the same, a primary and a secondary magnet for operating said switch, electromagnetic means controlling the successive o eration of said magnets, a slowacting re ay for controlling the operation of said electromagnetic means, and a contact in the circuit of said relay and controlled by said primary magnet.

6. In a telephone exchange system, a plurality of lines, a selector switch for interconnecting the same, an operating and a restoring magnet for said selector switch, electroinagnetic means for controlling the operation of said selector switch, and a means associated with each of said magnets for controlling the operation of said electromagnetic means.

In witness whereof, I hereunto subscribe my name this 4th day of September A. 1).,

BERT G. i 

